Olefinic metathesis in the presence of phenolic compounds

Abstract

According to the present invention there is provided a metathesis reaction between at least two olefinic compounds which are the same or different, each olefinic compound comprising a non-cyclic olefin or a compound which includes a non-cyclic olefinic moiety. The metathesis reaction is carried out in the presence of a Grubbs first generation catalyst and is characterised therein that it is carried out in the presence of a phenolic compound in the form of a phenol or a substituted phenol, which substituted phenol includes at least one hydroxyl and at least one further moiety other than H and OH attached to an arene ring.

Description

FIELD OF THE INVENTION [0001] This invention relates to the enhancement of a metathesis reaction between at least two olefinic compounds which are the same or different. BACKGROUND ART [0002] There is considerable interest regarding the formation of carbon-carbon bonds via olefin metathesis. The quest for highly active olefin metathesis catalysts has prompted considerable research efforts to develop olefin metathesis systems capable of tolerating a variety of functional groups. Ruthenium-based catalysts in particular have proven to be useful in catalysing olefin metathesis reactions, including cross metathesis (CM), ring-closing metathesis (RCM) and ring-opening metathesis polymerisation (ROMP) reactions. [0003] Olefin metathesis refers to the metal-catalysed redistribution of carbon-carbon double bonds. CM can be described as a metathesis reaction between two non-cyclic olefins, which may be the same or different, for example: [0004] Where the olefins are the same, the reaction is...

AI Technical Summary

Benefits of technology

[0069] The 1-octene metathesis reactions were performed following the general experimental procedure and using 200, 500 and 1000 equivalents of phenol, respectively. The results are shown in Table 2. Under these conditions, optimum performance is achievable with either 500 or 1000 equivalents of phenol. TABLE 2Metathesis of 1-octene with G1 + phenol (200, 500 and 1000eq).Molar % Conversion of 1-OcteneConditionsAfter 3 hG1 with no phenol added26%G1 + 200 eq phenol63%G1 + 500 eq phenol82%G1 + 1000 eq phenol77%

[0070] In an effort to asses the effect of substitution on the benzene ring of the phenol on the formation of 7-tetradecene in 1-octene metathesis, 500 equivalents of compounds 1-6 were added to the reaction mixture, following the general experimental procedure. The results are summarized in Table 3. TABLE 3Metathesis of 1-octene with substituted phenolsMolar % Conversion of 1-ConditionsOctene After 3 hG1 with no phenol added26.5%G1 + 500 eq 4-Cl-phenol (Compound 3)58.2%G1 + 500 eq 4-CF3-phenol (Compound 4)64.8%G1 + 500 eq 4-I-phenol (Compound 5)71.0%G1 + 500 eq 4-OMe-phenol (Compound 1)71.8%G1 + 500 eq phenol82.0%G1 + 500 eq 4-F-phenol (Compound 6)86.0%G1 + 500 eq 4-Me-phenol (cresol)91.1%(Compound 2)

[0071] These results show that the addition of 500 equivalents of p-cresol (compound 2) afforded very similar (but slightly better) yields compared to those obtained with phenol. 4-Methoxyphenol (compound 1) gave slightly lower conversions

Problems solved by technology

The production of bulk chemicals via ruthenium-catalysed metathesis, has the disadvantage that relatively high concentrations of costly ruthenium compounds are often required.

This is often in excess of 1 mol % of substrate which destroys the economic viability of such processes.

The use of suitably low catalyst concentrations is also confounded by the presence of impurities in typical olefinic feedstocks derived from primary processes such as naphtha cracking or the Fischer-Tropsch conversion of synthesis gas.

This change was attributed to an unquantified increase in catalyst activity.

However, the report of Grubbs and co-workers (J. Am. Chem. Soc. 1993, 115,9858-59) commented that whilst making the metal centre more electrophilic does lead to changes in the relative propagation rate of the ruthenium carbene centre in the polymerisation of norbornene, such complexes do not show improved activity for cross metathesis of pent-2-ene.

This again suggests that the above effect is restricted to propagation rates of certain ROMP reactions and is not generally applicable to all types of metathesis reactions.

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